Publications

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72 Publications visible to you, out of a total of 72

Abstract (Expand)

Cell signaling pathways are sequences of biochemical reactions that propagate an input signal, such as a hormone binding to a cell-surface receptor, into the cell to trigger a reactive process. Assessment of pathway activities is crucial for determining which pathways play roles in disease versus normal conditions. To date various pathway flow/perturbation assessment tools are available, however they are constrained to specific algorithms and specific data types. There are no accepted standards for evaluation of pathway activities or simulation of flow propagation events in pathways, and the results of different software are difficult to compare. Here we present Pathway Signal Flow Calculator (PSFC), a Cytoscape app for calculation of a pathway signal flow based on the pathway topology and node input data. The app provides a rich framework for customization of different signal flow algorithms to allow users to apply various approaches within a single computational framework.

Authors: L. Nersisyan, G. Johnson, M. Riel-Mehan, A. Pico, A. Arakelyan

Date Published: 25th Apr 2017

Publication Type: Journal

Abstract (Expand)

Background. Breast cancer is one of the most common cancers in women worldwide. The germline mutations of the BRCA1 and BRCA2 genes are the most significant and well characterized genetic risk factors for hereditary breast cancer. Intensive research in the last decades has demonstrated that the incidence of mutations varies widely among different populations. In this study we attempted to perform a pilot study for identification and characterization of mutations in BRCA1 and BRCA2 genes among Armenian patients with family history of breast cancer and their healthy relatives. Methods. We performed targeted exome sequencing for BRCA1 and BRCA2 genes in 6 patients and their healthy relatives. After alignment of short reads to the reference genome, germline single nucleotide variation and indel discovery was performed using GATK software. Functional implications of identified variants were assessed using ENSEMBL Variant Effect Predictor tool. Results. In total, 39 single nucleotide variations and 4 indels were identified, from which 15 SNPs and 3 indels were novel. No known pathogenic mutations were identified, but 2 SNPs causing missense amino acid mutations had significantly increased frequencies in the study group compared to the 1000 Genome populations. Conclusions. Our results demonstrate the importance of screening of BRCA1 and BRCA2 gene variants in the Armenian population in order to identity specifics of mutation spectrum and frequencies and enable accurate risk assessment of hereditary breast cancers. Keywords: BRCA1; BRCA2; breast cancer; mutation screening; targeted exome sequencing.

Authors: Sofi Atshemyan, Andranik Chavushyan, Nerses Berberian, Arthur Sahakyan, Roksana Zakharyan, Arsen Arakelyan

Date Published: 10th Jan 2017

Publication Type: Journal

Abstract (Expand)

Background: Schizophrenia (SCZ) is a multifactorial mental disease. Whereas complex interplay of genes and environment contributes to the SCZ, the disorder has still unclear biological background. Growing amount of evidence showed that synaptic dysfunctions are contributed to SCZ etiopathogenesis. The context and purpose of the study: Complexin-3, a presynaptic regulatory protein, represents here a special interest. This study was aimed to investigate the potential association of SCZ with rs3743487 single nucleotide polymorphism of the complexin-3 protein encoding gene (CPLX3). A total of 350 unrelated individuals of Armenian nationality (175 SCZ patients and the same number of age-, sex-matched healthy controls) were genotyped for the selected polymorphism using polymerase chain reaction with sequence-specific primers. Results and main findings: According to the results obtained, the frequency and carriage of the CPLX3 rs3743487*T allele did not differ in SCZ patients as compared to controls. Conclusions: We concluded that the CPLX3 rs3743487*T minor allele is not associated with SCZ in Armenian population. Brief summary: This study suggested no association of the CPLX3 rs3743487 polymorphism with schizophrenia, however, to clarify the role of the CPLX3 gene in SCZ further studies with much coverage of the gene and involvement of different methods are required.

Authors: Atshemyan Sofi, Zakharyan Roksana, Arakelyan Arsen

Date Published: 30th Dec 2015

Publication Type: Journal

Abstract (Expand)

The KEGG pathway database is a widely accepted source for biomolecular pathway maps. In this paper we present the CyKEGGParser app ( http://apps.cytoscape.org/apps/cykeggparser) for Cytoscape 3 that allows manipulation with KEGG pathway maps. Along with basic functionalities for pathway retrieval, visualization and export in KGML and BioPAX formats, the app provides unique features for computer-assisted adjustment of inconsistencies in KEGG pathway KGML files and generation of tissue- and protein-protein interaction specific pathways. We demonstrate that using biological context-specific KEGG pathways created with CyKEGGParser makes systems biology analysis more sensitive and appropriate compared to original pathways.

Authors: L. Nersisyan, R. Samsonyan, A. Arakelyan

Date Published: 13th Nov 2014

Publication Type: Journal

Abstract (Expand)

SUMMARY: KEGG pathway database is a collection of manually drawn pathway maps accompanied with KGML format files intended for use in automatic analysis. KGML files, however, do not contain the required information for complete reproduction of all the events indicated in the static image of a pathway map. Several parsers and editors of KEGG pathways exist for processing KGML files. We introduce KEGGParser-a MATLAB based tool for KEGG pathway parsing, semiautomatic fixing, editing, visualization and analysis in MATLAB environment. It also works with Scilab. AVAILABILITY AND IMPLEMENTATION: The source code is available at http://www.mathworks.com/matlabcentral/fileexchange/37561.

Authors: A. Arakelyan, L. Nersisyan

Date Published: 15th Feb 2013

Publication Type: Journal

Abstract (Expand)

Schizophrenia is a severe psychiatric disease with inflammatory component. Several studies indicated the increased blood levels of proinflammatory interleukin-6 cytokine in schizophrenia. However, only limited studies explored the relationship between excess production and genetic variations of this cytokine in schizophrenia, and the results were controversial. Here, we investigated possible association of the interleukin-6 gene (IL6) rs1800795 (–174G/C) polymorphism with schizophrenia and relationship between this polymorphism and interleukin-6 protein (IL-6) blood levels. This polymorphism was found by other researchers to associate with different transcription rates and different plasma levels of IL-6. A total of 208 unrelated Armenians were genotyped by polymerase chain reaction with sequence-specific primers, and IL-6 levels were assessed by enzyme-linked immunosorbent assay. The IL6 rs1800795 alleles and genotypes in both groups were in Hardy–Weinberg (H–W) equilibrium. We found that rs1800795*C allele [38% vs 24%, P = 0.002, odds ratio (OR) = 1.95, 95% confidence interval (CI): 1.18–2.14] and its carriers (62% vs 42%, P = 0.003, OR = 2.28, 95% CI: 1.13–1.94) were more frequent in patients than in controls. IL-6 in patients was 1.5-fold higher than in controls (mean ± SD: 6.41 ± 2.47 pg/ml vs 4.15 ± 1.42 pg/ml, P = 1.9E–19). In both groups, higher IL-6 in rs1800795 GG compared to rs1800795*C allele carriers was observed (GG vs GC + CC, patients: 7.02 ± 2.83 pg/ml vs 5.39 ± 1.2 pg/ml, P = 0.0006; controls: 5.21 ± 1.17 pg/ml vs 3.38 ± 1.03 pg/ml, P = 1.6E–15). In conclusion, we report an association of IL6 rs1800795 and higher IL-6 with schizophrenia. We also conclude that IL6 rs1800795*C allele is linked to increased IL-6 blood levels and may be a risk factor for schizophrenia development at least in Armenian population.

Authors: R. Zakharyan, M. Petrek, A. Arakelyan, F. Mrazek, S. Atshemyan, A. Boyajyan

Date Published: 10th May 2012

Publication Type: Journal

Abstract (Expand)

Monocyte chemoattractant protein-1 (MCP-1) has been proposed as a contributory factor in pathophysiology of schizophrenia. The aim of the current study was to explore the possible association of the MCP-1-2518A/G genetic polymorphism and plasma levels of MCP-1 in patients with paranoid schizophrenia. The MCP-1-2518A/G (rs1024611) polymorphism and blood levels of MCP-1 in patients with paranoid schizophrenia and healthy subjects were evaluated and compared. One hundred and three chronic patients with paranoid schizophrenia treated with neuroleptics and 105 healthy subjects were genotyped using polymerase chain reaction with sequence-specific primers (PCR-SSP) and their MCP-1 plasma levels were measured by a solid-phase enzyme-linked immunosorbent assay (ELISA). When comparisons were made between patients and controls, the frequency of the MCP-1-2518*G minor allele (35% vs 23%, p=0.009, OR=1.77, 95% CI: 1.1-2.04) and also of the MCP-1-2518*G carriers (60% vs 40%, p=0.003, OR=2.27, 95% CI: 1.13-2.01) were higher in patients. The mean value of the MCP-1 plasma level in patients with schizophrenia was significantly higher than in controls. Interestingly, the patients with the GG genotype had the highest MCP-1 level (711.4 ± 211.4 pg/ml), followed by those with the AG genotype (472.1 ± 135.8 pg/ml) and AA (372.4 ± 180.2 pg/ml) homozygotes. In conclusion, we report here the association of the -2518A/G genetic polymorphism and increased plasma levels of MCP-1 with schizophrenia and nominate -2518*G minor allele as a risk factor for schizophrenia in Armenian population.

Authors: Roksana Zakharyan, Anna Boyajyan, Arsen Arakelyan, Maya Melkumova, Frantisek Mrazek, Martin Petrek

Date Published: 17th Mar 2012

Publication Type: Journal

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